[gmx-users] Re: local pressure v4.5 issues

[Jianguo Li]

Hi Amit,

I also encountered the same problem you mentioned.
In v4.5, when using -nstlp wiht large value (e.g., 10000000), I got one file 
"localpressure.dat0". I tested first several frames of a trajectory, the 
calculated pressure is not the average of the pressure of individual frames. 

 
Btw, did you use CHARMM FF in your simulations and how did you convert the tpr 
files from v 4.5 to v 4.0?


Cheers
Jianguo




________________________________
From: Amit Choubey <kgp.amit at gmail.com>
To: Jianguo Li <ljggmx at yahoo.com.sg>; Discussion list for GROMACS users 
<gmx-users at gromacs.org>
Sent: Friday, 1 July 2011 10:32:07
Subject: Re: [gmx-users] Re: local pressure v4.5 issues

Hello Everyone,

The  git version of local pressure calculation at 


http://repo.or.cz/w/gromacs.git/shortlog/refs/heads/release-4-5-localpressure

is broken. I could not get it to work for my simulations.

I installed gromacs local pressure version 4.0 from

ftp://ftp.gromacs.org/pub/tmp/

I used gromacs-4.0.2_localpressure.tar.gz in that folder. 

The pressure values printed using this version seem reasonable to me. I 
converted all the tpr files from v 4.5 to v 4.0.

The output of the mdrun in v 4.0 is a single file "localpressure.dat" . On the 
contrary in v 4.5 there were separate "localpressure.dat*" files for each 
frame. 

I am not sure what exactly is the content of "localpressure.dat". Does it have 
the time averaged value of pressure tensor for each voxel ? It doesnt seem so to 
me because i tried it over only two frames (3 reruns were done for two frames 
separately and a .trr which had these two frames only) and the numbers did not 
seem to be averages.

Can someone help me in figuring out what is going on ?
Amit

On Tue, Jun 21, 2011 at 9:16 AM, Amit Choubey <kgp.amit at gmail.com> wrote:


>
>
>On Tue, Jun 21, 2011 at 1:13 AM, Jianguo Li <ljggmx at yahoo.com.sg> wrote:
>
>Hi Amit,
>>
>>May I ask you a question? 
>>In your calculation of local pressure using a trajectory file, did you get a 
>>single averaged localpressure.dat file? Or else you get a bunch of separate 
>>files for each frame (e.g., localpressure.dat0, localpressure.dat1, 
>>localpressure.dat2 ....)?
>>

>Yes I do get different files for different trajectories. All the files seem to 
>have the same problem ie a very large/small number printed as tensor elements of 
>the pressure for some of the voxels.
>
>
>Do you have such problems ? Could we compare our methodologies to use the local 
>pressure version ?
>
>Amit
>
>>Thank you very much!
>>
>>Cheers,
>>Jianguo
>>
>>
>>
>>
>>
________________________________
From: Amit Choubey <kgp.amit at gmail.com>
>>To: Discussion list for GROMACS users <gmx-users at gromacs.org>
>>Sent: Monday, 20 June 2011 07:08:03
>>Subject: [gmx-users] Re: local pressure v4.5 issues
>>
>>
>>Dear all,
>>
>>
>>I did another simulation with only SPC water. Then I used the local pressure 
>>gromacs to calculate the stresses. It seems to be reasonable. 
>>
>>
>>I am not sure how to figure out what goes wrong with my previous simulations 
>>when plugged into the local pressure gromacs.
>>
>>
>>Could someone help me in figuring out whats the issue ?
>>
>>
>>Thank You.
>>
>>
>>On Fri, Jun 17, 2011 at 6:00 PM, Amit Choubey <kgp.amit at gmail.com> wrote:
>>
>>Dear all,
>>>
>>>I installed the git version of local pressure calculation from 
>>>
>>>http://repo.or.cz/w/gromacs.git/shortlog/refs/heads/release-4-5-localpressure
>>>
>>>The I invoked mdrun
>>>
>>>mdrun_lp -v -s rerun.tpr -g rerun_log -olp -rerun traj0.gro -localpgrid 0.1
>>>
>>>This created a file named "localpressure.dat0". This is a binary file so I could 
>>>not look at it directly. I am not sure if there is a tool in the gromacs to look 
>>>at it directly. 
>>>
>>>
>>>To look at the data in "localpressure.dat0" I used the planar_av.c code 
>>>available in "pressure-tools" folder at
>>>
>>>http://md.chem.rug.nl/cgmartini/index.php/3d
>>>
>>>When I look at the Pressure tensor averaged over xy plane, some of the numbers 
>>>are reasonable but few of them are ridiculously large numbers which is not 
>>>expected. 
>>>
>>>
>>>I checked this on two different simulations and I got the same problems. The 
>>>simulations had run OK previously.
>>>
>>>Could someone help me in figuring our whats going on ?
>>>
>>>Amit Choubey
>>>
>>>
>>
>
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